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Topic: 67 68 Camaro manual drum brakes (Read 68295 times)

It would be difficult to see them. They are behind the valve seat in the outlet holes. You might be able to see them if you used a strong light but what you would likely observe would be a black edge. I think this would be difficult especially if you didn't know what to expect to see. Take a fine wire and VERY gently probe the hole to see if you feel anything. Don't "push" it because you don't want to take a chance of rupturing the valve. The valve has a slit in the top of it so, as I said in the above post, you could hit it just right and go past the top of it thinking you didn't have a valve there. But if you are careful and move the wire from side to side you should feel the rubber valve. Be careful.

OK, I can confirm that the NAPA UP472 rebuild kit comes with the RPVs. It also comes with what I assume are the self-tapping screws needed to pull the original seats. However, the kit that came in from the warehouse has brass seats that were all corroded. I didn't dare use them, so they ordered another kit for me.

I wonder if it is possible to pull the existing seats without damaging them and then re-install them. The new seats had a counterbore on the back side that the RPV sits in. Maybe the existing seats don't have this since there are no RPVs in there. Anyhow, I'll try to keep you posted on my progress.

Jeff, I can't imagine how you would remove the existing ones without damaging them. I would not risk reusing them even if you could pull them as they might "loose the fit" if you know what I mean. As for myself I would use the new ones.....just my 2cents. BTW, if the next NAPA kit has corroded ones in it and there is an Advance Auto near they carry the kit as well, however, the supplier may be the same as for NAPA. http://www.partsamerica.com/ProductDetail.aspx?MfrCode=RAY&MfrPartNumber=MK472&PartType=229&PTSet=A

Steve-Yeah, you're right about re-using the seats. I came to the same conclusion after thinking about it for a little bit.

Funny, I actually called the local Advance Auto right after I posted and they told me they didn't sell the Raybestos kit, even after I gave them the part number. I ended up ordering the Raybestos kit through a local CarQuest. They will have it on Friday. I hope that the quality will be better than the NAPA kit, but, like you said, they are probably the same manufacturer.-Jeff

Yes it is original and i overhauled it myself 3 times allready. The bore is pitted and last about 2 to 3 yrs until i have to rebuild it.I have since then purchased 1 in California last year at a swap meet for 5 bucks. The guy i think did not no what it was worth to me. Also if you use a small drill bit on the flat side you can feel the check valve spring back n forth. Only on the rear port.

Great idea on the drill bit! Odd that it only had the check valve on the rear only. To the best of your knowledge then no one had replaced the seats before? We are talking about your original mc and not the one you bought at the swap meet right?

Yes i am talking about original one. The other one is identical eccept for casting date. I am in the process of rebuilding the swap meet one to put in car. The MC turned out to be rebuildable and clean. I replaced the brass seat last time and left the check valve alone. The rear line is still original and it tightened the seat up. When done i should not have to remove MC again.

Yes, the drill bit is an excellent idea. I just used the flat end of a small bit on my MC, and I'm now 100% sure that SSBC did not install the required RPVs.Steve- Wouldn't it make sense that red67l78's MC only has one RPV since it is a disc brake car?

Steve... I wouldn't rule out a bad master cylinder, new OR rebuilt. When I started to reassemble my '68--manual drum brakes all around--I went through 3 before I got a good one. The first two would not bench-bleed right--perhaps the check valves were stuck or installed wrong, who knows--but neither worked as it should. The 3rd one was okay and works perfectly. Just a thought...

There is no question that the mc's that I tried did not have check valves in them. I called the manufactures and both advised that they did not install them in their products. After installing the one Cardone made for me with check valves in both outlets, the car has the best braking one could ask for. The pedal is both high and firm and over the past two weeks has continued to provide great breaking. BTW, before returning the replaced mc to the store I pulled the seats just to confirm for myself that there were no check valves (there were none) and the other mc's that I had tried did bench bleed very well, they just didn't have the check valves.

I just finished installing the RPVs in my original MC. Not too bad of a job. Here are a few diagrams showing the RPV (check) valves:

I couldn't get the supplied 6-32 self-tapping screw to 'start', so I drilled & tapped the existing seats.A little grease (Permatex brake caliper grease that is compatible with all brake system rubber parts) on the drill to capture the brass chips:

Same goes for the tap:

Tapping the seat:

Install the tube nut, then install a 6-32 screw long enough to engage all the threads you just tapped:

Hold the screw from turning and back out the tube nut:

Here is one of the original seats after removal:

Clean everything thoroughly, then install the RPV, then the seat, then the tube nut, and tighten the tube nut until the seat bottoms out. Do the same on the other port and you are done. The finished project:

Sorry I forgot to take pictures of the actual valves. When I got to that part I guess I got a little anxious to get everything installed.